1. Field of the Invention
This invention relates to a process for preparing ethylene glycol by reaction of carbon monoxide and hydrogen in the presence of a catalyst, a promoter and a solvent. In another embodiment, this invention is concerned with the preparation of ethylene glycol ethers from carbon monoxide and hydrogen.
2. Prior Art
In recent years, a large number of patents have been issued dealing with the synthesis of lower molecular weight hydrocarbons, olefins, alkanols etc. from synthesis gas. Of particular note, U.S. Pat. No. 2,636,046, discloses the synthesis of polyhydric alcohols and their derivatives by reaction between carbon monoxide and hydrogen at elevated pressures (&gt;1500 atm or 22000 psi) and temperatures of &gt;150.degree. C. using certain cobalt-containing catalysts. The reaction of carbon monoxide and hydrogen in the presence of a ruthenium catalyst and a pyridine base ligand to form ethylene glycol is set out in U.S. Pat. No. 4,170,605. Also recently, in Belgium Pat. No. 793,086 and U.S. Pat. No. 3,940,432 there is described the co-synthesis of methanol and ethylene glycol from mixtures of carbon monoxide and hydrogen using a rhodium complex catalyst. Typically, CO-hydrogenation is effected at 8000 psi of 1:1 H.sub.2 /CO synthesis gas, at 220.degree. C., using tetraglyme as the solvent. and dicarbonylacetylacetonatorhodium(I) in combination with promoters such as pyridine and its derivatives as the catalyst precursor. (For summary of the work, see: R. L. Pruett, Annals New York Academy of Sciences, Vol. 295 p. 239 (1977)). While other metals of Group VIII of the Periodic Table have been tested for activity under similar conditions, including cobalt, ruthenium, copper, manganese, iridium and platinum, only cobalt was found to have slight activity. The use of ruthenium compounds in particular failed to produce polyfunctional products such as ethylene glycol. This is illustrated in U.S. Pat. No. 3,833,634 for solutions of triruthenium dodecacarbonyl.